The present invention relates to a process for preparing low-foaming nonionic surfactants and more particularly to a process for preparing ether-capped poly(oxyalkylated) alcohol surfactants which have superior spotting and filming benefits in dishwashing and hard surface cleaning applications, as well as suds suppression in detergent compositions.
Due to the varied nature of different cleaning compositions, different surfactants are better suited for some applications while being less suited or totally unsuitable for other applications. Nonionic surfactants, such as alcohol ethoxylates and alkyl glucose amides, are of considerable importance in detergent products. Under some conditions, nonionic surfactants aid cleaning of greasy soils and inhibit the formation of calcium soap. However, conventional nonionic surfactants designed for effective cleaning in laundry products form liquid crystalline phases on mixing with water. These phases can hinder the rate of mixing with water and lead to undesirable optical properties of thin films on solution drying. For example, conventional nonionics sprayed on the surface of granules to achieve target density can give rise to poor granule dissolution and residue in horizontal axis machine dispensers. Conventional nonionics formulated at high levels in liquid products can lead to poor rates of mixing with water. Conventional nonionics in window and floor cleaners can form visible liquid crystalline films on drying that increase the effort required by the consumer to achieve good results. Similarly, a nonionic surfactant for use in an automatic dishwashing machine would need to minimize foam production and not leave undesirable spots and films on the cleaned surfaces.
On account of the foregoing technical constraints as well as consumer needs and demands, product compositions are undergoing continual change and improvement. Moreover, environmental factors such as the need for biodegradable materials, the restriction of phosphate, the desirability of providing ever-better cleaning results with less product, and the use of less thermal energy and less water to assist the washing process, have all driven the need for improved compositions.
Accordingly, the need remains for new surfactants that are suitable for use in a variety of compositions which can provide improve dissolution of solid products (like bars and tablets) and granular products, improved rates of mixing of liquid products with water, improved streaking and filming performance in hard surface cleaners and automatic dishwashing products, and good cleaning, suds control and biodegradability, while avoiding incompatibility with other cleaning surfactants and/or bleach.
In accordance with a first aspect of the present invention, a process for preparing an ether-capped poly(oxyalkylated) alcohol surfactant is provided. The surfactant has the formula:
RO(R1O)xCH(CH3)OR2 
wherein R is selected from the group consisting of linear or branched, saturated or unsaturated, substituted or unsubstituted, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R1 may be the same or different, and is independently selected from the group consisting of branched or linear C2 to C7 alkylene in any given molecule; x is a number from 1 to about 30; and R2 is a six membered substituted or unsubstituted, saturated or unsaturated, cyclic or aromatic hydrocarbon radical.
The process comprises the steps of:
(a) providing a vinyl ether of the formula
R2OCHxe2x95x90CH2 
xe2x80x83wherein R2 is as defined above;
(b) providing an alkoxylated alcohol of the formula
RO(R1O)xH 
xe2x80x83wherein R, R1, and x, are as defined above;
(c) reacting the vinyl ether with said alkoxylated alcohol in the presence of a catalytically effective amount of a catalyst to form the ether-capped poly(oxyalkylated) alcohol, wherein reaction of the vinyl ether with the alkoxylated alcohol is conducted as a temperature of from about 0xc2x0 C. to about 60xc2x0 C. and said catalyst is a sulfonic catalyst; and
(d) quenching the reaction of step (c) by the addition of a base.
These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (xc2x0 C.) unless otherwise specified. All documents cited are in relevant part, incorporated herein by reference.
Once again, the present invention is directed toward a process for producing a low-foaming nonionic surfactant for use in detergent and other cleaning compositions.
It has been surprisingly discovered in accordance with the present invention that significant improvements in spotting and filming characteristics and, when used in conjunction with high cloud point surfactants, in the removal of greasy soils relative to conventional surfactants, are provided via the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention.
The novel surfactants of the present invention comprise ether-capped poly(oxyalkylated) alcohols having the formula:
RO(R1O)xCH(CH3)OR2. 
In one aspect of the present invention R is a linear or branched, saturated or unsaturated, substituted or unsubstituted, aliphatic hydrocarbon radical having from about 1 to about 30 carbon atoms, preferably from about 1 to about 20 carbon atoms. Even more preferably, R is a linear or branched, saturated, aliphatic hydrocarbon radical having from about 4 to about 18, preferably from about 8 to about 16, carbon atoms.
In the present invention R2 is a six membered substituted or unsubstituted, saturated or unsaturated, cyclic or aromatic hydrocarbon radical.
In another embodiment of this aspect of the present invention R2 is selected from the group consisting of: 
wherein each R3 is independently selected from the group consisting of hydrogen and linear or branched, saturated or unsaturated, substituted or unsubstituted, aliphatic hydrocarbon or alkoxy radicals having from about 1 to about 10 carbon atoms; or each R3 is a saturated or unsaturated, substituted or unsubstituted, alicyclic or aromatic hydrocarbon radical having from about 1 to about 10 carbon atoms, which is fused to the ring; and w is an integer from 1 to 3.
In another embodiment of this aspect of the present invention R2 is selected from the group consisting of: 
wherein each R3 is defined as above.
In another embodiment of this aspect of the present invention R2 is selected from the group consisting of: 
In one aspect of the present invention, when x is greater than 2, R1 may be the same or different. That is, R1 may vary between any of the C2 to C7 alkylene units as described above. For instance, if x is 3, R1 may be selected to form ethyleneoxy(EO) or propyleneoxy(PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, multiple (EO) units and a much smaller number of (PO) units. Similarly, ethylene, and propylene are chosen for example only and the variation may be much larger with selection of linear or branched butylene, pentylene, hexylene and/or heptylene. Preferably, x is from about 2 to about 20, and each R1 is ethylene or propylene. More preferably, x is from about 4 to about 12, and each R1 is ethylene.
The surfactants of the present invention can be prepared via the following process.
In one embodiment of this aspect of the present invention the step of reacting of vinyl ether with alkoxylated alcohol is conducted in the presence of a sulfonic catalyst. Suitable sulfonic catalysts include sulfonic acids and their salts such as p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, 4-bromobenzene sulfonic acid, naphthalenesulfonic acid, (xc2x1)-10-camphorsulfonic acid, xylenesulfonic acid, cumenesulfonic acid, alkylbenzene sulfonic acids and mixtures thereof.
Preferred catalysts include methanesulfonic acid and p-toluenesulfonic acid.
Mixtures of catalysts are also within the scope of the present invention. Similarly, the uses of supported, such as in a column for a continuous reaction, and unsupported catalysts are also within the scope of the present invention.
The catalysts are preferably employed at amounts of about 0.005 mol % to about 20.0 mol %, more preferably from about 0.01 mol % to about 10.0 mol %, even more preferably from about 0.01 mol % to about 5.0 mol %, even more preferably still from about 0.01 mol % to about 1.5 mol %, based on the number of moles of alkoxylated alcohol in step (c) of the process.
In one embodiment of this aspect of the present invention the reaction is conducted in the presence of a solvent, or mixtures of solvents. It is preferred that the solvent be a polar aprotic solvent. Suitable solvents include, but are not limited to, hexane, benzene, toluene, xylene, mesitylene, dichloromethane, tetrahydrofuran, dioxane, chloroform, diethylether, methyl tert-butylether, acetone, acrylonitrile, or the like. Furthermore, the reaction is conducted at temperatures ranging from about 0xc2x0 C. to about 60xc2x0 C., and more preferably from about 10xc2x0 C. to about 60xc2x0 C. Lastly, the reaction is preferably conducted at pressures ranging from about 0.5 atmospheres to about 100 atmospheres, and more preferably from about 0.8 atmospheres to about 10 atmospheres.
In another embodiment of this aspect of the present invention the step of reacting vinyl ether with alkoxylated alcohol is conducted in the absence of a solvent.
Further disclosure on suitable solvents and catalysts can be found in xe2x80x9cAdvanced Organic Chemistryxe2x80x9d, by Jerry March, 4th ed., Wiley-Interscience, 1992, xe2x80x9cComprehensive Organic Transformationsxe2x80x9d by Richard C. Larock, VCH Publishers, 1989, and xe2x80x9cProtective Groups in Organic Synthesisxe2x80x9d 3RD ed. by Theodora W. Greene and Peter G. M. Wuts, Wiley-Interscience, 1999 the relevant portions of which are incorporated herein by reference.
In one embodiment of the present invention, the process is performed as a batch process. That is, the reaction is let to proceed to completion, or near completion, and then final product is removed. In another embodiment of the present invention, the process is performed as a continuous process. That is, the product of the process is continuously removed from the reaction vessel while starting material is added at a comparable rate.
In one embodiment of the present invention the vinyl ether is reacted with the alkoxylated alcohol at a mole ratio of from about 5:1 to about 0.5:1, more preferably from about 3:1 to about 0.75:1, more preferably still from about 1.5:1 to about 0.9:1.
In one embodiment of the process of the present invention the process may be conducted in an inert gas. This may be done by sparging with any suitable inert gas, such as nitrogen, helium, neon, or argon.
In the process of the present invention, step (d) is a step in which the reaction step (c) is quenched by the addition of base. The amount of the ether capped poly(oxyalkylated) alcohol surfactant present in the reaction mixture will depend upon many factors, including but not limited to, starting materials, temperature, catalyst selection and the like. Quenching stops the reaction of the starting materials, and ensures that any ether capped poly(oxyalkylated) alcohol surfactant produced does not undergo further reaction or revert back to the starting materials. The quenching of step (c) produces a mixture which contains ether capped poly(oxyalkylated) alcohol surfactant, as well as unreacted starting materials, catalyst and the products of any side reactions. In one embodiment of this present invention, the quenching of the reaction of step (c) is done when the reaction mixture preferably contains at least 90%, more preferably at least 95% by weight of ether capped poly(oxyalkylated) alcohol surfactant. The remaining portion of the mixture, up to 10%, more preferably up to 5% by weight, comprises unreacted starting material as well as products of side reactions, such as byproduct acetals. In one aspect of this embodiment of the present invention the base may be optionally selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkali metal hydroxides, alkali metal alcoholates, alkanolamines, alkylamines, aromatic amines and mixtures thereof. In a further aspect of the present invention the base may be optionally selected from the group consisting of potassium carbonate, sodium carbonate, sodium bicarbonate, sodium methoxylate, sodium ethoxylate, potassium tert-butyloxylate, triethylamine, triethanolamine and mixtures thereof. In another aspect of this embodiment of the present invention, the base may be in the form of an aqueous solution. In a further aspect of this embodiment of the present invention, the aqueous solution may be at a temperature of from about 20xc2x0 C. to about 60xc2x0 C.
The expression xe2x80x9cproduct of step (c)xe2x80x9d is meant to include not only the ether-capped poly(oxyalkylated) alcohol surfactant but also any unreacted starting materials or any materials produced from side reactions which would be present at the conclusion of step (c).
In one embodiment of the present invention the process of the present invention may optionally further comprise a step (e). Step (e) is removal of color bodies and/or odors from the product of step (c). In one aspect of this embodiment of the present invention removal of the color bodies and/or odors is obtained by contacting the product of step (c) with a reagent. The reagent can either be an oxidant, or a reductant. Suitable oxidants include hydrogen peroxide. Suitable reductants include sodium borohydride, and hydrogen over a palladium/carbon catalyst. In a further aspect of this embodiment of the present invention the color bodies and/or odors are removed by contacting the product of step (c) first with an oxidant and then a reductant, or first with a reductant and then an oxidant. The color bodies may also be removed by treating the product mixture with activated charcoal (carbon).
In one embodiment of the present invention the ether-capped poly(oxyalkylated) alcohol surfactant produced in steps (c) or (d) may optionally be removed from the product of steps (c) or (d) by centrifuging.
A representative example of this synthetic route of this aspect of the invention is demonstrated via the following diagram. 
The ether-capped poly(oxyalkylated) alcohol surfactant product is then collected by means common in the art such as extraction. If desired, the surfactant may be further treated by stripping, distillation or various other means before use. The surfactant made by the process disclosed herein may contain related impurities, which will not adversely affect performance.
The following examples are illustrative of the present invention, but are not meant to limit or otherwise define its scope. All parts, percentages and ratios used herein are expressed as percent by weight unless otherwise specified.